1. Field of the Invention
The present invention relates to a support for the drive shaft of an axial-piston machine of inclined axis construction (pivoted or tilted drum) for pressurized fluids, consisting of at least one axially loadable bearing arranged at respectively, the piston side and at the drive side with stationary outer rings arranged in a bearing housing and a load-receiving direction located the same towards the piston side. At least the outer ring of one of the bearings is axially supported on the bearing housing and at least one of the inner rings of the bearing is supported on the drive shaft at the piston side shaft and whereby, for balancing the axial components of the piston forces effective between the bearings, there is provided at least one pressure cylinder unit with a balancing piston which is acted upon with pressurized fluid from the pressure side of the machine.
The drive shaft support of inclined-axis axial-piston machines has to transmit primarily axial forces. Hereby one usually intends to distribute these forces over a plurality of parallel operating bearings whereby, however, a uniform load distribution which requires an extraordinarily precise coordination in effect, over the entire load range with consideration being given to the changing rotational speed and pressure loading of the machine also not being theoretically precisely possible. The uneven loading of the ball or roller bearings is the essential criterium for the high wear thereof.
2. Discussion of the Prior Art
Previously known hydraulically supported axial friction bearings are not suited for high rotational speeds, since they are sensitive to foreign bodies and temperature variations and produce a continuous oil leakage loss which reduces the efficiency of the machine. In order to avoid these disadvantages, from German Published Patent Application No. 1,210,681 it has become known to transmit without play only a portion of the occuring axial forces through roller bodies on a track fixed on the housing, while the remainder of the axial forces are hydrautically transmitted through radially or axially offset and yieldably arranged roller bearing tracks in dependence upon the working pressure of the drive fluid.
In the bearing support of the previously mentioned type which has become known from German Laid-open Patent Application No. 21 12 822, the two axially loadable bearings are constructed as radiax bearings, in effect, deep groove-type radial ball bearings, in order to relieve the higher loaded piston-sided radiax bearing from the axial components of the piston forces and to distribute on the parallel operating drive-sided radiax bearing; for transmission of the axial forces to the bearing housing, the drive shaft together with the drive disc and with a shoulder on the shaft is supported on the inner rings of the two radiax bearings which are provided with different diameters. For the distribution of the axial forces over the two bearings, the stationary outer ring of the drive-sided axial bearing is indirectly supported on the housing, whereas the larger diameter outer ring of the piston-sided axial bearing is positioned against a balancing piston which is subjected to the machine pressurized fluid.
This drive shaft bearing is constructively complicated since, due to the stepped construction of the drive shaft and of the housing inner wall, it requires precise tolerances and a high production demand. However, it is a significant disadvantage that, for the supply of the balancing piston with machine pressurized fluid, there is required a high pressure-resistant bearing housing through which, in a usual manner, the pressure-sided machine pressurized fluid is introduced through a passageway.
The same disadvantage encountered with respect to the required high pressure-resistant bearing housing is present in German Laid-open Patent Application No. 27 40 821 in the bearing support therein of principally the same type. Therein, balancing pistons lie against the outer ring of the drive-sided radial bearing. The inner ring of the piston-sided radiax bearing is supported by means of a spacer sleeve which is mounted on the drive shaft against the inner ring of the drive-sided radiax bearing. A further disadvantage of this solution consists of in that, ahead of the drive-sided radiax bearing, there is additionally required a sufficiently large constructional space for the balancing pistons. Inasmuch as for combined radiax bearings there is sought the largest possible bearing distance for the reduction of the radial forces, through consideration of the bearing length, the building space in this known solution cannot be utilized entirely in an optimum manner. Moreover, the supply with machine pressurized fluid must be effected over a lengthy path, in effect, from one end of the other of the entire axial piston machine.